Fossil fuels and carbon dioxide have long been absorbed by our worlds oceans. We once thought this was acceptable because the oceans were invincible. Too big to be moved by our petty games. However, we recently learned this was not the case. We found that the pH in our oceans is decreasing. In other words it is becoming more acidic. The pH of our ocean has dropped by 25% (-0.1 pH) from over a century ago. By 2100 the projection is that the ocean pH would have reduced from 8.1 to 7.7. This ocean would be three times more acidic than it is now. 

 An article in Science Daily shows how researchers working on the Australian sea urchin, Heliocidaris erythrogramma, have examined reproductive success under increasing acidity. Following the 2100 projections they reduced the acidity, where sea urchins were held, from 8.1 to 7.7 pH. They then measured the number of gametes (sperm and eggs) released. Sea urchins are external fertilisers and so release their gametes into the water column. They found that the number of gametes released dropped 25%. This suggests that populations of this species would decline as acidification increases. Unless of course more of these gametes grow through to adult stage? However, this is a warning sign not just for the sea urchin but also for other commercially and ecologically important species as well such as fish, crustaceans and corals.